The Minnesota Department of Health is investigating after a nine-year-old boy died of a suspected amoeba infection.
Health officials said Tuesday the boy apparently died of a rare form of meningitis caused by an amoeba, known as Naegleria fowleri, commonly found in warm freshwater and soil. It infects people by entering the body through the nose and causes severe brain infection that is nearly always fatal.
"The risk of infection from Naegleria in Minnesota is very low," said Richard Danila, Assistant State Epidemiologist, in a statement. "Swimming is a very healthy summertime activity and we do not want to discourage people from swimming. Rather, simply avoid swimming, diving or other activities in obviously stagnant water when temperatures are high and water levels are low," Danila said.
The infection usually occurs in the southern U.S. Minnesota's only previously confirmed case was reported in August 2010.
Danila said that until that incident two years ago there had only been about 125 cases of this form of meningitis in the United States since 1925.
Health officials say the boy had gone swimming at various locations in Washington County two weeks before getting sick, including Lily Lake in Stillwater. That lake was the likely source of infection in Minnesota's previous case. Lily Lake is closed to swimming until further notice.
"We do worry about this because we know that temperatures are increasing and we know that water temperatures are increasing," Danila said. "There's a risk but it's a very small risk, the risk would be greater for smaller, shallower areas where the water can get very hot and amoeba can proliferate."
The Associated Press contributed to this report